Error elbow code: 25a236 - motor encoder index missing

Technical Questions Robot Communication
1

I have a UR3 CB Series robot, purchased in 2023. The robot started experiencing the ‘Motor Encoder Index Missing’ error in 2025. It initially affected elbow 3, and every time I run it, the robot always displays a ‘Motor Encoder Index Missing’ notification. I checked the error manual and found that this ‘Motor Encoder Index Missing’ error requires a joint replacement. Financially, replacing the motor every year is not feasible.

Is this a common problem with the UR3 CB series, or are there any preventative measures we can take?

2

It requires an electrical repair of the joint, which is much cheaper than a new joint. You don’t have to replace it, but you’ll have to ship it to UR and wait quite some time.

As far as I know, there are no preventative measures for this error. It is definitely the most frequent error on the CB3s, and it doesn’t seem to be affecting the e-series or the new UR series.
The CB3 series is also discontinued by now, if I’m not mistaken.